STUDIES ON THE FLUORESCENCE EMISSION SPECTRA AND ENERGY TRANSFER OF PHYCOBILISOMES FROM SPIRULINA PLATENSIS IN THE COURSE OF DISSOCIATION
螺旋藻（Spirulina　platensis）藻胆体在解离过程中荧光发射光谱和光能传递的研究

Fluorescence emission spectra of phycobilisomes from Spriulila platensis in 0.1, 0.3, 0.6 and 0.9 mol/L phosphate buffer at different times of dissociation were studied at room temperature and 77K. There were three bands in 77K fluorescence spectrum of dissociated phycobilisomes: F655,F666 and F687,characteritic respectively of C-phycocyanin(C-PC),allophycocyanin (APC)and allophycocyanin-B (APC-B). But there was only F687 in that of intaCt phycobilisomes (in 0.9 mol/L phosphate buffer).When phycobilisomes Dissociated, F655 appeared before F666. It shoed that the linkage between C-PC and APC was more unstable than that of APC and APC-B.Phycobilisomes in 0.3 mol/L phosphate biber for 1 min, the fluorescence maxima was shifted from 687 um to 684 um. and then F655 appeared and increased rapidly.At 10 min,the main fluorescence peak was located at 684 um F655 continued to increase,and F666 appeared. At 30 min, both F655 and F666 inCreaSed, and the relahve fluorescence of F655 was higher than that of F666 and F684,indication that phycobilisornes dissodated severely.At 2 h,F655 inrmed, F684 decreased,and F666 disappears. It indicatal that the energy rapted by C-PC Couldn't transfer to APC,one links with APC,the other links with APC-B. The phycobiliproteins in phycobilisomes of S. platensis constitute energy transfer chain, shown as follows.Phycobilisiomes in 0.1 mol/L phosphate buffer for 2 h, only C-PC fluorescence emission band was observed. The phycobilisomes dissocated completely,and the energy couldn't tranfer from C-PC iD APC and APC-B.